You can’t manually input chain length values (or at least I don’t think you can). You have feed out the chain using the Actions → Set Chain Length - Automatic. But, before you do so, go to Advanced Settings and make sure the Extend Chain Distance equals 1651. Then, after you extend the chain and right after you attach the sled (don’t do a return to center or hit any other buttons) mark the links that are sitting on the top sprocket tooth with something. This will allow you to quickly reset the chain lengths if you ever have to again…